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Q&A: Tracking the source of stomach bug outbreak

WASHINGTON — Is an outbreak of a nasty stomach bug over? Depends on who you ask.

Iowa officials say that almost 150 cyclospora infections in their state were linked to a bagged lettuce mix and the threat is over. Federal officials at the Centers for Disease Control and Prevention and the Food and Drug Administration aren't so sure, saying it is too early to say if the outbreak is over. There are almost 400 illnesses total in 15 states.

Here are some answers to frequently asked questions about the infections and the outbreak:

Q: What are cyclospora infections?

A: Cyclospora infection, or cyclosporiasis, is caused by parasites that are spread when people ingest food or water contaminated with feces. People who are exposed usually become sick after about a week and have bad diarrhea and other flu-like symptoms that can last from a few days to a month or longer if untreated. It's common to feel tired and relapse is possible. It's not generally contagious and can be treated with antibiotics. Deaths from the infection are rare.

Q: Who is usually at risk?

A: People who live or travel in tropical or subtropical countries are most at risk, according to the CDC. The infections are rare in the United States but have been linked in the past to imported fruits and vegetables.

Q: I heard it is linked to bagged salad. Should I stop eating bagged salad?

A: It's not clear. The illnesses are in 15 states, but only two of those states, Iowa and Nebraska, are saying that it is linked to bagged salad mix. The CDC and FDA say they don't yet have enough information to say what is causing the illnesses.

Iowa officials have said they believe the affected salad has already spoiled and is no longer in the supply chain. They have said they believe the salad was served in restaurants, was in the food service chain and also sold at stores, but they won't say where the salad mix came from. Nebraska officials said the salad mix in question included iceberg and romaine lettuce, along with red cabbage and carrots that came through national distribution chains.

Q: Am I at risk in this current outbreak?

A: Probably not, but federal officials aren't ready to declare it over. The state officials say it appears to have passed, but a CDC spokeswoman says "it's too early to say for sure whether it's over, and thus too early to say there's no risk of still getting sick."

María-Belén Moran of the CDC says the agency "is still conducting an investigation and working to determine if the conclusions from Iowa and Nebraska help explain the increased numbers of cases in other states."

The last reported illness began July 18, and there have only been seven reported illnesses since July 6. Fifteen states have so far reported illnesses: Arkansas, Connecticut, Florida, Georgia, Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, New Jersey, New York, Ohio, Texas and Wisconsin.

Q: How does the government trace the source of illnesses like this?

A: It takes a lot of legwork and coordination between states and the federal government. Cases are confirmed when a sick person gives a sample to his or her doctor and that sample is tested. If it is positive, it will eventually be reported to a state health department. The states then gather that data and coordinate with the CDC to look for common strains that could link the illness to a specific product. State and federal officials interview the victims and closely question them about what they ate around the time they fell ill — often a difficult task, as it is hard for most people to remember everything they ate over an extended time.

Q: Why is this particular outbreak so hard to trace?

A: Cyclospora infections are rare in this country so state health departments aren't as accustomed to tracing them as they are more common U.S. foodborne illnesses like salmonella and E. coli. It is also difficult because cyclospora usually doesn't show up until a week after a person has eaten the tainted food, so it's harder for people to remember what they ate.

In this outbreak, the Food and Drug Administration says its investigators have been trying to trace the paths of the food eaten by those who fell ill. Food often goes through several stops — potentially in several countries — before it reaches a grocery cart, and the FDA said the process is "labor-intensive and painstaking work, requiring the collection, review and analysis of hundreds and at times thousands of invoices and shipping documents."

The agency said it has a seven-person team in its Maryland headquarters and specialists in 10 field offices across the country working to identify the source of the outbreak.

Q: What else do we know about this outbreak?

A: Not much. Iowa officials have said the salad mix wasn't grown in Iowa or Nebraska but won't say where it was grown or sold. The Iowa officials say that because there is no immediate threat, they are not required to say where the food came from. Food safety and consumer advocates disagree, saying the public has a right to know the source even if the tainted food is out of the commercial chain.

Q: What can I do to prevent contracting an illness like this?

A: Short of growing all of your own food, it may be unavoidable. All foods — including those labeled local, natural or organic — have the potential to be exposed to safety hazards on the farm, in transit or in the store. Sometimes all it takes is one rogue animal that broke through a fence or one employee who didn't do proper handwashing to infect food. If irrigation water is infected, that can sicken people too. Sometimes pathogens or parasites can be washed off the surface of food but other times they are deep inside, so anyone who eats it is at risk of becoming sick.

What you can do is make sure you practice safe handling and preparation. The FDA recommends always washing hands, utensils and surfaces with hot, soapy water before and after handling food. You should also thoroughly wash all fresh produce before you eat it. Those measures should significantly reduce your chances of getting sick.